Referring to FIG. 1, FIG. 1 is a schematic view showing a cross-portion of an OLED display panel in the related art, the OLED display panel mainly includes a base substrate 101, a reflective metal layer 102, an anode 103, a hole transport layer (HTL) 104, an emitting layer (EML) 105, an electron transport layer (ETL) 106, a semi-transparent metal cathode 107 and a light extraction layer 108. The hole transport layer 104, the emitting layer 105, the electron transport layer 106 and the metal cathode 107 are films manufactured by vacuum evaporation process. Mask plates used in the vacuum evaporation process include a fine metal mask (FMM) and an open mask. Usually, the metal cathode 107 is vacuum-evaporated by using the open mask, thereby to obtain a metal cathode formed as a whole layer.
Since the metal cathode has strong absorption and strong reflection against light, thus there is a great loss of light in an OLED display panel including the metal cathode formed as a whole layer, resulting in a very low light extracting rate (referring to FIG. 2), arrows in the figure represent directions of light. In addition, since the metal cathode has strong reflection against light, thus a micro-cavity effect is formed in the OLED display panel. One defect of the micro-cavity effect is that display color changes significantly with different viewing angles.